Nixon spoke at the Love, Peace and Marriage Equality rally, a pro-gay marriage gathering, in New York City Sunday. The red-maned actress told the crowd — which included her Sex co-star Kristen Davis, David Hyde Pierce, Audra McDonald and Ana Oritz — of her engagement, while showing off a glimmering diamond ring.

Nixon, a mother-of-two, left her then-husband Danny Mozes six years ago, and has been involved with Marinoni ever since.

The sequel to last year’s hit adaptation of the HBO series will be released in theaters May 28, 2010. (Photo: WENN)